dsh-git-manager: A Visual GitHub Git Manager for DeepSeek Harness

`dsh-git-manager` is a visual Git management plugin for DeepSeek Harness (DSH), replacing the original `gitcompass`. It provides GitHub-Flow guidance, commit graphs, branch/PR/Issue management, and exposes a structured tool interface to agents. The plugin supports Device Flow OAuth login, real-time monitoring of agent activity, and an In-Panel approval mechanism; it follows DSH themes, supports Sidebar or Dock mode, and ensures Git operations remain tightly integrated with DSH agents.